EPIDEMIOLOGY AND GENETICS OF ATOPIC DERMATITIS IN SINGAPORE

Ph.DDOCTOR OF PHILOSOPH

Variation in Uteroglobin-Related Protein 1 (UGRP1) gene is associated with Allergic Rhinitis in Singapore Chinese

<p>Abstract</p> <p>Background</p> <p>Uteroglobin-Related Protein 1 (<it>UGRP1</it>) is a secretoglobulin protein which has been suggested to play a role in lung inflammation and allergic diseases. UGRP1 has also been shown to be an important pneumoprotein, with diagnostic potential as a biomarker of lung damage. Previous genetic studies evaluating the association between variations on <it>UGRP1 </it>and allergic phenotypes have yielded mixed results. The aim of this present study was to identify genetic polymorphisms in <it>UGRP1 </it>and investigate if they were associated with asthma and allergic rhinitis in the Singapore Chinese population.</p> <p>Methods</p> <p>Resequencing of the <it>UGRP1 </it>gene was conducted on 40 randomly selected individuals from Singapore of ethnic Chinese origin. The polymorphisms identified were then tagged and genotyped in a population of 1893 Singapore Chinese individuals. Genetic associations were evaluated in this population comparing 795 individuals with allergic rhinitis, 718 with asthma (of which 337 had both asthma and allergic rhinitis) and 717 healthy controls with no history of allergy or allergic diseases.</p> <p>Results</p> <p>By resequencing the <it>UGRP1 </it>gene within our population, we identified 11 novel and 16 known single nucleotide polymorphisms (SNPs). TagSNPs were then genotyped, revealing a significant association between rs7726552 and allergic rhinitis (Odds Ratio: 0.81, 95% Confidence Interval: 0.66-0.98, P = 0.039). This association remained statistically significant when it was analyzed genotypically or when stratified according to haplotypes. When variations on <it>UGRP1 </it>were evaluated against asthma, no association was observed.</p> <p>Conclusion</p> <p>This study documents the association between polymorphisms in <it>UGRP1 </it>and allergic rhinitis, suggesting a potential role in its pathogenesis.</p

Genome-wide association study identifies PERLD1 as asthma candidate gene

10.1186/1471-2350-12-170BMC Medical Genetics12-BMGM

Toll-like receptor 3 agonist, polyinosinic-polycytidylic acid, upregulates carbonic anhydrase ii in human keratinocytes

Carbonic anhydrases are ubiquitously expressed enzymes that reversibly hydrate carbon dioxide to bicar-bonate and protons. While the main function of carbonic anhydrases is to regulate pH and osmotic balance, their involvement in other physiological processes remains to be explored. This study analysed changes in mRNA and protein levels of carbonic anhydrase II in human primary keratinocytes treated with various toll-like receptor agonists and cytokines. A significant upregulation of carbonic anhydrase II at the mRNA and protein levels was observed upon treatment with polyinosinic-polycytidylic acid, a toll-like receptor 3 agonist. Furthermore, in agreement with the increased expression of carbonic anhydrase II in atopic dermatitis skin, carbonic anhydrase II was upregulated by the Th2 cytokines interleukins-4 and-13. In conclusion, these results suggest a potential role of carbonic anhydrase II in Th2-dependent and toll-like receptor 3-induced pathways in inflammatory skin conditions

Different phenotypes and factors associated with atopic dermatitis in the young adult Singaporean Chinese population: A cross-sectional study

Background: Atopic dermatitis (AD) is a chronic allergic disease typically accompanied by atopy and thus, a tendency to develop allergic diseases such as allergic rhinitis, asthma or food allergies. Currently, individuals with AD are classified into those presenting with AD alone and those presenting with AD along with other allergic diseases (AD+). It is important to identify the various endophenotypes of AD using anthropometric, environmental, socio-economic, and disease history data in order to improve disease management. To characterize the phenotypic differences among Singaporean Chinese individuals with AD alone and AD+, and identify the socioeconomic, lifestyle, and environmental factors associated with these different presentations. Methods: Based on data collected via a standardized/validated questionnaire, 4604 participants (mean age: 22.1 years) were classified into three groups: 1) AD alone group; 2) AD with other allergic diseases group (AD+); and 3) Control group. Results: Participants were less sensitized to common inhalant allergens in the AD alone group versus the Control group (67% vs. 72%, respectively; p  23) was associated with the disease and the difference was more pronounced in the AD alone group compared to the AD+ group (Odds Ratio: 1.38; 95% Confidence Interval: 1.4–1.67; p < 0.001). No major differences in habits were observed between the AD alone and AD+ groups. Conclusions: The two presentations of AD may have different underlying pathogenesis and associated risk factors. Keywords: Atopic dermatitis, Allergy, Singaporean Chinese population, Phenotypes, Risk factor

A functional brain-derived neurotrophic factor (BDNF) gene variant increases the risk of moderate-to-severe allergic rhinitis

Background: Brain-derived neurotrophic factor (BDNF) is a secretory protein that has been implicated in the pathogenesis of allergic rhinitis (AR), atopic asthma, and eczema, but it is currently unknown whether BDNF polymorphisms influence susceptibility to moderate-to-severe AR.Objective: We sought to identify disease associations and the functional effect of BDNF genetic variants in patients with moderate-to-severe AR.Methods: Tagging single nucleotide polymorphisms (SNPs) spanning the BDNF gene were selected from the human HapMap Han Chinese from Beijing (CHB) data set, and associations with moderate-to-severe AR were assessed in 2 independent cohorts of Chinese patients (2216 from Shandong province and 1239 living in Singapore). The functional effects of the BDNF genetic variants were determined by using both in vitro and ex vivo assays.Results: The tagging SNP rs10767664 was significantly associated with the risk of moderate-to-severe AR in both Singapore Chinese (P = .0017; odds ratio, 1.324) and Shandong Chinese populations (P = .039; odds ratio, 1.180). The coding nonsynonymous SNP rs6265 was in perfect linkage with rs10767664 and conferred increased BDNF protein secretion by a human cell line in vitro. Subjects bearing the AA genotype of rs10767664 exhibited increased risk of moderate-to-severe AR and displayed increased BDNF protein and total IgE levels in plasma. Using a large-scale expression quantitative trait locus study, we demonstrated that BDNF SNPs are significantly associated with altered BDNF concentrations in peripheral blood.Conclusion: A common genetic variant of the BDNF gene is associated with increased risk of moderate-to-severe AR, and the AA genotype is associated with increased BDNF mRNA levels in peripheral blood. Together, these data indicate that functional BDNF gene variants increase the risk of moderate-to-severe AR.</p

A functional brain-derived neurotrophic factor (BDNF) gene variant increases the risk of moderate-to-severe allergic rhinitis

Background: Brain-derived neurotrophic factor (BDNF) is a secretory protein that has been implicated in the pathogenesis of allergic rhinitis (AR), atopic asthma, and eczema, but it is currently unknown whether BDNF polymorphisms influence susceptibility to moderate-to-severe AR. Objective: We sought to identify disease associations and the functional effect of BDNF genetic variants in patients with moderate-to-severe AR. Methods: Tagging single nucleotide polymorphisms (SNPs) spanning the BDNF gene were selected from the human HapMap Han Chinese from Beijing (CHB) data set, and associations with moderate-to-severe AR were assessed in 2 independent cohorts of Chinese patients (2216 from Shandong province and 1239 living in Singapore). The functional effects of the BDNF genetic variants were determined by using both in vitro and ex vivo assays. Results: The tagging SNP rs10767664 was significantly associated with the risk of moderate-to-severe AR in both Singapore Chinese (P = .0017; odds ratio, 1.324) and Shandong Chinese populations (P = .039; odds ratio, 1.180). The coding nonsynonymous SNP rs6265 was in perfect linkage with rs10767664 and conferred increased BDNF protein secretion by a human cell line in vitro. Subjects bearing the AA genotype of rs10767664 exhibited increased risk of moderate-to-severe AR and displayed increased BDNF protein and total IgE levels in plasma. Using a large-scale expression quantitative trait locus study, we demonstrated that BDNF SNPs are significantly associated with altered BDNF concentrations in peripheral blood. Conclusion: A common genetic variant of the BDNF gene is associated with increased risk of moderate-to-severe AR, and the AA genotype is associated with increased BDNF mRNA levels in peripheral blood. Together, these data indicate that functional BDNF gene variants increase the risk of moderate-to-severe AR